Seznam abstraktů 2024: POSTEROVÁ SEKCE E

Controlling nanoparticles (NPs) morphology in laser-mediated synthesis remains a significant challenge. This study introduces an innovative approach for synthesizing metal NPs using an Optical Vortex Beam (OVB) instead of the conventional Gaussian Beam (GB) in femtosecond laser ablation in liquids (fs-LAL). The primary objective is to achieve NPs shape modification through an environmentally friendly method, eliminating the need for chemical reagents and producing ligand-free NPs suitable for catalytic and biomedical applications. The transformation from GB to OVB was accomplished using a series of waveplates that first converted the linearly polarized GB to a circularly polarized beam and subsequently to a spiral phase wavefront beam, known as OVB. A key innovation of this study is the design of a 3D-printed ablation cell, which generates a thin liquid layer and ensures continuous liquid flow over the metal target, optimizing the laser-ablation setup. This optimization not only enhances productivity but also significantly reduces operation time. Results indicate that using OVB provides superior control over NPs morphology compared to GB, resulting in NPs with improved optical properties, as confirmed by Scanning Transmission Electron Microscopy (STEM) and UV-Vis spectroscopy. This approach holds potential for nanocatalysis, offering a cleaner and more efficient method for NPs synthesis.

Hyaluronan (HA) is a biopolymer abundant in the human body that can be grafted by acyl chains. Due to their amphiphilic character, hydrophobically modified HA (H-HA) materials can form nanocapsules with sizes from tens to hundreds of nm in combination with an oil phase. The hydrophilic hyaluronan shell preserves the desired properties of hyaluronan for the resulting emulsions (biocompatibility, mucoadhesion, etc.), and grafted hydrophobic chains stabilize the oil phase. Oils not only ensure high solubility of hydrophobic active substances, but they also have positive effects on the human body. Therefore, combining H-HA with oils appears promising for cosmetic and pharmaceutical formulations.
Nanocapsules were prepared from H-HA with various chemical compositions using different oil phases. Nanocapsules were characterized by several physico-chemical techniques, such as dynamic light scattering, nanoparticle tracking analysis, confocal fluorescence microscopy, or fluorescence. H-HA’s chemical compositions significantly influenced the size of the nanocapsules. The influence of both aqueous and oil phase compositions on nanocapsules’ size and stability was also observed. Therefore, the nanocapsules can be tailored for different applications, such as topical or oral. Nanocapsules were found stable in the aqueous dispersion for an extended period. Hydrophobic active compounds were loaded into the oil phase, and their performance in nanocapsules was studied.

Polymer materials exhibit significant structural changes in response to an external electric field, which is important for various applications such as electrospinning technology [1]. This study explores the structural properties of oligo(ethylene glycol) (OEG) with different chain lengths in water and methanol under an external electric field, using extensive molecular dynamics simulations. These simulations aim to elucidate the findings of our previous research [2].
We analyze the size and shape anisotropy of the oligomer chain by measuring the end-to-end distance, radius of gyration, and other metrics derived from the gyration tensor. Additionally, we calculate the distributions of dihedral angles, the cosine of angles between the CC vectors of the COC segments and the OO vectors of the OCCO segments, and the dipole moments of the chain and solvents with respect to the electric field. To quantify the helicity of the chain, we count the monomer units in predefined helical patterns.
Our results show that the initially isotropic chain in both solvents becomes increasingly anisotropic, adopting an oblate shape as the electric field intensity increases. However, in water, this effect diminishes with increasing chain length and eventually reverses, leading to a prolate shape. The population of the gauche conformation also increases significantly with higher field intensity. In methanol, the CC vectors of the COC segments and the OO vectors of the OCCO segments align perpendicular to the electric field. In water, however, the OO vectors shift to smaller angles, while the CC vectors remain perpendicular to the field. Additionally, the dipole moments of both the chain and solvents increasingly align with the direction of the electric field.
Acknowledgements: This research has been supported by the Jan Evangelista Purkyně University in Ústí nad Labem within the student grant programme (Project No. UJEP-SGS-2022-53-002-3). Computational resources were supplied by the project "e-Infrastruktura CZ" (e-INFRA LM2018140) provided within the program Projects of Large Research, Development and Innovations Infrastructures.
REFERENCES: [1] Jirsák, J., P. Pokorný, P. Holec a Š. Dědičová: A Molecular-Level Picture of Electrospinning. Water, 12(9):2577:1-31, 2020; [2] Dědičová, Š., J. Dočkal, F. Moučka a J. Jirsák: Molecular dynamics simulation study of the effect of a strong electric field on the structure of a poly(oxyethylene) chain in explicit solvents. Journal of Molecular Liquids, 338(2):116622, 2021.

Periodic nanostructures formed on solid surfaces by ion bombardment were first observed in the mid-20th century. Following the initial observations, number of theoretical and experimental results have been published on this topic. In our experimental work, micro- and nanoscale surface structures were created using focused gallium ion beam at two different energies.
During the low-energy (2 kV) ion irradiation, with the ion incident angle of between 60 and 80 degrees, regular ripple formations with characteristic size of 30 - 70 nm were produced. The optical properties of the formed nanostructured surfaces were investigated by spectroscopic ellipsometry and reflectometry to reveal industrial application possibilities. Based on the results, the reflectance of the created surfaces can be fine-tuned by the change of the ion incidence angle.
In addition by the 30 kV ion irradiations, structures with dimensions comparable to the wavelength of the visible light were fabricated. Detailed examination was carried out for the ~35 degree of incidence angle case, where diverse morphologies were observed. These results can also provide the basis for further applications.

Alpha spectrometry is an extremely useful and sensitive for detection of alpha-emitting nuclides. Contamination of the silicon detectors for low-level alpha spectrometry by recoil nuclides is a serious problem in the measurement of alpha emitters decaying to daughter nuclides with short half-lives. This unwanted contamination leads to decreased measurement sensitivity causing a degradation of the limit of detection. The simplest method to prevent this radioactive contamination of detector is to use a catcher film between the alpha source and the detector. In this work we describe the obtaining of the thin Formvar films as stopper foils for recoil nuclei and we investigated the influence of these films on alpha spectrometry parameters, as energy shift (30 keV) and resolution (7%). No significant deterioration of the alpha spectrometry parameters was observed when using thin Formvar films. Using the ASTAR web databases, which calculate stopping powers for alpha particles, the thickness of Formvar films was estimated to be about 5.355 9 10-5 g/cm2. The measurements were performed with an AlphaQuatro SELENA alpha spectrometer with Si implanted detector.

Square planar geometry in coordination complexes can be achieved in late transition metal ions,1 e.g, in metal-containing phthalocyanines (MPcs), which are embedded in a π-conjugated macrocycle with a high degree of planarity allowing stacking in the solid state. The electron rich environment promotes interactions with gas analytes, leading to measurable physical changes2 and making them suitable candidates for chemiresistive sensing. We have investigated new chemiresistive sensing materials using square-planar Ni(II) complexes with oxime ligands based on substituted salicylaldehydes. These complexes are relatively stable under sublimation conditions, making them good candidates for thin film deposition and possible gas sensing which can be varied by the different substituents on the benzene moiety.3
Three Ni(II) complexes 4-7 were synthesized, purified by sublimation, and fully characterized. Thin films of various thicknesses were deposited using low-temperature high-vacuum evaporation. Deposition parameters, including substrates, temperature, deposition rate, and vacuum pressure were optimized to achieve uniform and homogeneous films with desirable morphological and structural properties. The thin films were fully characterized and AFM and SEM images revealed long needle-like crystals with a very high aspect ratio indicating a very large surface area for the interaction of analyte gas molecules.
ACKNOWLEDGEMENTS: This work was supported by the Czech Science Foundation (GačR grant number: 23-05878S) and the OP-JAC project financed by European Structural and Investment Funds and the Czech Ministry of Education, Youth and Sports (Project No. SENDISO - CZ.02.01.01/00/22_008/0004596).

Zinc oxide (ZnO is a low cost and environmentally friendly material with unique optical properties and variety of nano and microstructures imposing challenges for energy conversion, scintillators, photocatalytic wastewater treatment, electrochemical energy storage or sensing applications. In our previous work [1] we have presented the results on ZnO thin films prepared by reactive magneton sputtering of Zn target in pure oxygen atmosphere. We have shown that plasma hydrogenation effectively suppresses ZnO defects, leading to a significant increase in electrical conductivity and exciton-related UV luminescence. We found good room temperature stability of the plasma hydrogenated ZnO nanocrystals in air, but fast degradation at elevated temperature.
In this work, the nominally undoped and Al-doped ZnO thin films were pulsed laser deposited (PLD) on commercial interdigitated gold 5/5 µm and 10/10 µm (electrode width/electrode gap) gold electrodes (MicruX Technologies, Spain) were tested by impedance and photocurrent spectroscopy. To further study the surface-related effects, we employed a custom-built inductively coupled plasma (ICP) 13.56 MHz reactor with up to 300 W RF discharge power and exposed ZnO samples to the ICP plasma with a mixture of hydrogen and argon for up to 30 min.
The work was supported by the Czech Science Foundation project 24-10607J, Ministry of Education, Youth and Sports of Czech Republic (MEYS) Danube project 8X23025 and the Mobility Plus project SAV-23-13 (CAS-SAS-2022-08). The authors also acknowledge the Czech Ministry of Education, Youth and Sports grant no. CZ.02.01.01/00/22_008/0004617 − "Energy conversion and storage".
[1] Remes Z, Chang Y Y, Stuchlik J and Micova J 2019 The photoluminescence and optical absorptance of plasma hydrogenated nanocrystalline ZnO thin films NANOCON 2018 - Conference Proceedings 10th International Conference on Nanomaterials - Research and Application, 17-19 October 2018 (Hotel Voronez I, Brno, Czech Republic: TANGER Ltd., Ostrava) pp 78-82

The aim of the present work is to develop an industrial-size reactor for plasma-enhanced chemical vapor deposition (PECVD). We used our small GEC geometry reactor as a template. The reactor is powered with an RF power supply through a matching unit. Initial experiments demonstrated successful transferability and reproducibility of diamond-like carbon thin film deposition processes from the smaller reactor.
In the subsequent step, the focus shifted to the production of nanocomposite copper-doped thin films with antibacterial and antiviral properties. These films are deposited from a mixture of methane and a precursor containing fluorine and copper atoms: (hfac)copperVTMS (hfac = hexafluoroacetylacetonato and VTMS = vinyltrimethylsilane). The deposited thin films underwent comprehensive analysis using nanoindentation techniques, including thermal testing, atomic force microscopy, and X-ray photoelectronic spectroscopy. Moreover, the water contact angle measurement was used to perform a preliminary test of the film's adhesion to the substrate.
ACKNOWLEDGMENT: This research has been supported by projects LM2018096 and LM2023039, funded by the Ministry of Education, Youth and Sports of the Czech Republic, and by project TN01000038, funded by the Technology Agency of the Czech Republic.

Tin alloys have historically been used in a wide range of products, from organ pipes and everyday items to jewellery. In more recent times, industrial applications have included food cans and a significant proportion of electrical-engineering products, especially those using Pb-Sn solders. While Pb-containing ones were recently banned in favor of lead-free solders, the need of basic research of tin is more important than ever. In this theoretical study, we applied quantum-mechanical calculations to investigate the thermodynamic and dynamic stability of tin in its various allotropic forms. Specifically, phonon spectra and vibrational contributions to free energy were computed for the cubic diamond-structured alpha tin, as well as the body-centered tetragonal beta tin and metastable hexagonal gamma tin, using the harmonic approximation and quasi-harmonic approximation.
Focusing specifically on the alpha-Sn, our results showed a negative thermal expansion in it within the temperature range from T = 0 K to T = 45 K. No similar phenomenon appears in spectra of other allotropic modifications of tin. That means that origin of this behaviour is connected to the diamond structure of alpha tin. I investigated behaviour of Grüneisen constant of alpha tin in reciprocal space to explain causes of this phenomenon. There are interesting temperature-dependent contributions of individual phonon modes from different k-points in the reciprocal space. In particular, these contributions are negative at all studied temperatures for the k-points around k-point X (0, 0, 0.5) and positive around k-point Γ (0, 0, 0). Negative thermal expansion of alpha tin at low temperatures is related to behaviour of phonons around k-points X, M and N.
ACKNOWLEDGEMENTS: Financial support from the Czech Science Foundation, project "Causes and mechanisms of degradation of tin-based materials with a low content of alloying elements" No. 22-05801S, is gratefully acknowledged. Computational resources were provided by the e-INFRA CZ project (ID:90254), supported by the Ministry of Education, Youth and Sports of the Czech Republic. These resources were utilized through IT4Innovations National Supercomputing Center, MetaCentrum as well as CERIT Scientific Cloud.

In the present work the local mechanical properties of TZnSb (T=Pd, Ti, V, Cr) alloys with promising thermoelectric properties were studied using a fast nanoindentation technique: the accelerated mechanical property mapping (XPM) mode. This mode enables to obtain hardness and elastic modulus maps on multiphase materials with high spatial resolution and low acquisition times. Compared to the classical quasistatic grid indentation method the XPM measuring method is substantially faster. Large number of nanoindentation data (over 1000) was acquired using the above-described method.
Several different phases may be distinguished on the mechanical property maps. According to the statistical distribution of nanoindentation data compared to the analytical electron microscopy results it was possible to evaluate the mechanical properties of the different phases of TZnSb materials.
ACKNOWLEDGEMENTS: This research was supported by MEYS, Czech Republic via the bilateral Mobility project 8J23AT014 co-sponsored by the Austrian WTZ-CZ08/2023 and by Czech Science Foundation under project GA23-06263S.

Calcination of phyllosilicate/organics nanocomposites in inert atmosphere leads to in situ formation of graphitic carbon layers on silicate phases. Electrically conductive material (ceramics) is thus obtained. Despite an intensive research in this area, attention has not yet been paid to carbon/silicate interfaces in these systems. This study is focused on structure compatibility of graphitic carbon and the most abundant phases formed by transformation of aluminum phyllosilicates or magnesium phyllosilicates, i.e. cristobalite, mullite, forsterite, and protoenstatite. The aim is to find whether the phases can or cannot have a significant influence on the graphitic structure formation, and if the type of phyllosilicate (aluminum or magnesium) must be taken into account. Structure compatibility is determined by original method calculating the overlaps of atomic pairs carbon/another element. Carbon atoms lie in graphite(001) plane, atoms of another element lie in the given phase(hkl) plane. Different crystallographic planes of phases formed from the original phyllosilicates exhibit various structure compatibility with the graphite. The average number of overlaps of individual graphite(001)/phase(hkl) systems revealed the highest structure compatibility for mullite (M) followed by forsterite (F), protoenstatite (P) and cristobalite (C), namely M(102) > F(001) > P(100) > C(100). This sequence suggests that aluminum phyllosilicates, from which M is formed, could be a more suitable input component compared to magnesium phyllosilicates, from which F and P are formed. The significantly lower number of overlaps for C compared to other phases indicates its small contribution to the overall structural compatibility. This work was supported by SGS project No. SP2024/041.

Evolution of surface morphology and defects formation are investigated in high fluence nitrogen ion implanted TiNbZrTa beta titanium alloy. Ion implantation was performed with nitrogen ions with a fluence up to 9∙1017cm-2 and an accelerating voltage of 90 kV. Changes in surface morphology were well observable for applied fluence of approximately 3∙1017cm-2 and higher. Surface defects in the form of blisters, a typical sign of oversaturation, were found. Well visible cracking of the surface nitride layer and the presence of surface pores were observed. Self-service pores covered the entire surface, including the area of sputtered blisters at the highest fluence.

Scanning Thermal Microscopy is an established technique for measurements of local thermal properties of solid samples at nanoscale or microscale. It is based on using a small resistive heater on an apex of Scanning Probe Microscope probe, which can then sense local temperature or generate heat. Local thermal conductivity can be evaluated from the losses when probe is heated. However, in this configuration it is impossible to determine the parameters of anisotropic materials. By extending the technique to use of two probes simultaneously, we can control the direction of the heat flow and address more complex phenomena. The first experimental realization of the technique suffered by the heat flow between the probes via air, making the quantitative analysis almost impossible. Here we present a vacuum version of the setup which significantly improves the measured signals as is demonstrated in various measurement configurations.

Gwyscope was developed as a low cost alternative for SPM controllers. Heard of Gwyscope is a low cost RedPitaya FPGA board enhanced by additional AD and DA converters, so it is capable of dimensional, mechanical, electrical and magnetic measurements including various sensing principles. It is also highly flexible, we can set up multiple controllers for dedicated tasks in one experiment.
In this contribution, we will present results obtained with Gwyscope being a controller in Scanning Near-field Optical Microscope (SNOM). It will be demonstrated that it can be used to control probe-sample distance based on shear force, which is typical for aperture SNOM. We will show that we can simultaneously acquire topography and optical data on various samples not only in a standard configuration where only one laser wavelength in used, but also in a custom built SNOM enhanced for hyperspectral measurements.

Detailed mapping of e.g. mechanical or thermal material properties using techniques such as scanning probe microscopy or instrumented indentation can be a very lengthy process. However, acquiring the complete image might not be needed e.g. when looking for a specific feature. We present a custom software tool, which, when possibly combined with a suitable measuring instrument, enables to quickly identify regions containing anomalies, and to gather information from suspect regions in the first place.
The foundation for the tool is provided by iteratively employing Gaussian processes (GP), which can be considered a form of machine learning, and can be applied as an interpolation tool, able to predict the function value as well as the variance (uncertainty) of the prediction at a given point. GP can be implemented in computer using standard tools for linear algebra and optimization without need for large computation toolboxes.
With our tool in each iteration, a GP is constructed and trained using data already acquired, and then used to suggest regions (points, lines) not yet measured where uncertainty of the prediction is greatest - this typically corresponds to areas in which the measured quantity changes noticeably. Performing the measurement at the suggested regions provides quick reduction of the overall uncertainty on the whole unmapped area. The procedure is then repeated until sufficient amount of information is gathered.

Silicon carbide (SiC) is one of the most extensively studied and utilized materials for self-healing applications due to its excellent thermal and mechanical properties. Several methods can be employed for SiC preparation, including combustion, high-energy milling, carbothermic reduction, chemical vapor synthesis, and the sol-gel technique. In our work, we focus on the sol-gel method, utilizing liquid phases of tetraethyl orthosilicate (TEOS) as the silicon source, solution of saccharose as the carbon source, and hydrochloric acid as the catalyst.
Various initial parameters, such as reactant concentrations, pH levels, and temperatures of sol, were selected to investigate their influence on the sol formation and the characteristics of the final SiC product. Throughout the preparation process, Fourier-transform infrared (FTIR) spectroscopy was employed to monitor the chemical changes and track the formation of characteristic bonds. The final products were further characterized using FTIR and X-ray diffraction (XRD) analysis to confirm their crystalline structure and evaluate their phase composition and DLS was used for particle size evaluation. This approach provides critical insights into how the sol-gel method and its parameters affect the material quality of SiC.
ACKNOWLEDGEMENTS: This work was supported by M-ERA.NET joint research project SAFER No. TH82020004 and by the financial support of the European Union under the REFRESH - Research Excellence For REgion Sustainability and High-tech Industries project number CZ.10.03.01/00/22_003/0000048 via the Operational Programme Just Transition.

The photocatalytic activity of materials still cannot be determined by molecular simulations. Therefore, all photocatalytic activity of the materials is determined experimentally in laboratories. However, existing standard measurements are not free from disadvantages, and the whole measurement process is time-consuming. Therefore, we present the possibility of in situ measurement of the photocatalytic activity of powder materials. The in situ method is based on differences in laser absorption by the tested dye. The results were compared with the standard method for measuring photocatalytic activity, and a good similarity was observed.

Scanning Thermal Microscopy (SThM) is a Scanning Probe Microscopy (SPM) technique allowing the measurement of local temperature, thermal conductivity and local thermomechanical properties down to the nanoscale.
In order to obtain quantitative results, calibration and traceability are of critical importance. Direct calibration of the instrument is not possible and reference samples must be used instead. The calibration curve depends strongly on the properties of the thermal probe and as such is susceptible to wear. Thus the calibration curve should be measured together with the unknown samples. The resulting time requirements, sensitivity to wear and the fact that there only few reference samples are available limit the number of calibration points. The determination of the thermal conductivity of the unknown samples thus depends on fitting of few data points with considerable uncertainty with a nonlinear calibration curve. This represents a metrological challenge that needs complex data processing. In this contribution we present the acquisition of the calibration points, notably their uncertainty analysis, and the subsequent numerical analysis based on an algorithm for the both curve fitting and single step evaluation of local thermal conductivities and their uncertainties, simplifying this procedure.

The work focuses on the development of a linear electrode for the production of flat nanofibrous material by spinning a polymer solution using the AC electrospinning technique. This method is characterized by high productivity and the absence of an electrically active collector, which predisposes it to the production of advanced nanofibrous structures that will find application in medical and technical applications such as filtration or tissue engineering.
Current spinning electrodes for AC electrospinning are characterized by a working surface with a overcritical electric field intensity, from which polymer jets and subsequent nanofibers are created in all directions. A spatial, hollow nanofibrous plume is created by the natural periodic interconnection of fibers in the area of the virtual collector. The transport and deposition of such a nanofibrous structure on the supportive spunbond is unstable, when due to the air emerging from the inner space with higher concentration of the residual solvent, folds and other defects are created.
By the geometrically modified electrodes with the help of simulation tools for electric field analysis, it is possible to efficiently modify the geometry and the working surface of the electrode so that the nanofibers are formed only in a single plane, thereby eliminating the negative effects of the spatial nanofibrous plume.
Based on the analyses, electrodes capable of continuous operation producing nanofibers in the single plane and in the desired direction producing a planar nanofiber structure are developed and tested.
With the use of these advanced devices, it is possible to produce more homogeneous surface layered nanofiber materials and advanced nanofiber structures for use especially in medical applications.

Knowledge of mineral composition of rocks is essential for determining their properties and subsequent applications. Nowadays, analysis of mineral composition of rocks can be performed by several methods. The most commonly used method is X-ray diffraction. Raman spectroscopy represent a non-destructive and rapid alternative, which (unlike X-ray diffraction) allows the use of handheld instruments. A major disadvantage of using Raman spectroscopy in rock analysis can be the presence of intense fluorescence in the spectra, which very often causes a significant loss of spectral information. In this study, we deal with the possibility of using Raman spectroscopy as a tool for quantifying the mineral composition of claystones and clay shales. Samples from different locations were measured by dispersive Raman spectrometer using laser with wavelength of 633 nm. The measured spectra were affected by the presence of strong fluorescence and overlapping bands. Therefore, the quantification was based on the development of multivariate calibration models using the partial least squares regression method (PLSR). Multivariate calibration models were developed for three predominant minerals - quartz, muscovite and chlorite. Validation of calibration models was performed by cross-validation.
ACKNOWLEDGEMENTS: This work was supported by the SGS project no. SP2024/041.